The present embodiments relate to computer networks and are more particularly directed to a method for traffic engineering in a multi-homed Virtual Private Local Area Network Service of a Metro Ethernet Network.
Ethernet networks have found favor in many applications in the networking industry for various reasons. For example, Ethernet is a widely used and cost effective medium, with numerous interfaces and capable of communications and various speeds up to the Gbps range. Ethernet networks may be used to form a Metro Ethernet Network (“MEN”), which is generally a publicly accessible network that provides a Metro domain, typically under the control of a single administrator, such as an Internet Service Provider (“ISP”). A MEN is typically used to connect between an access network and a core network. The access network typically includes private or end users making connectivity to the network. The core network is used to connect to other Metro Ethernet Networks, and the core network provides primarily a packet switching function.
A MEN typically consists of a number of Provider Edge (“PE”) nodes that are identified and configured for communicating with one another prior to the communication of packet traffic. The PE nodes are connected in a point-to-point manner, that is, each PE node is connected to another PE node in an emulated and bi-directional virtual circuit manner, where each such connection is achieved by a Label Switched Path (“LSP”). An LSP is sometimes informally referred to as a link. Thus, each PE node may communicate to, and receive packets from, an adjacent PE node. Further, along each LSP, between adjacent PE nodes, are often a number of Provider (“P”) nodes. The P nodes maintain no state information and serve primarily a routing function and, thus, are understood not to disturb the point-to-point connection between the PE nodes of the MEN, which are more intelligent devices. A different number of P nodes may be connected in one communication direction between two adjacent PE nodes as compared to the reverse communication direction between those same two adjacent PE nodes.
PE nodes in the MEN are also coupled to one or more Customer Edge (“CE”) nodes, where those CE nodes thereby represent the interface between the MEN and an adjacent access network. Often in the art, the coupling of a PE node to a CE node is through an intermediate node between the PE node and the CE node, where such an intermediate node is referred to as a layer 2 Provider Edge (“L2PE”) node. The connectivity between an L2PE node and additional PE nodes in the MEN is typically referred to as homing. More particularly, if the L2PE node is connected to a single PE node, then the connection is referred to as a single home; in contrast, if the L2PE node is connected to more than one PE node, then the connection is referred to as multi-homed. Further, while L2PE nodes may be multi-homed (i.e., connected to more than one other PE node), the CE nodes of any adjacent access network may not, that is, each CE node may connect to only a single L2PE node.
With the development of the MEN architecture, there have further evolved additional topologies associated with such a network. One example, that pertains to the preferred embodiments that are described later, is the virtual private local area network service (“VPLS”). A VPLS creates an emulated local area network (“LAN”) segment for a given set of nodes in a MEN. The VPLS delivers an ISO layer 2 broadcast domain that is fully capable of learning and forwarding on Ethernet MAC addresses that is closed to a given set of nodes. Thus, within the VPLS, packets may be broadcast to all nodes on the VPLS. VPLS also may be included within the above-described framework that includes PE and L2PE nodes, subject to various constraints. First, more than one VPLS may be included in a single MEN and, thus, certain PE nodes of that MEN may be a part of more than one VPLS. Second, with a multiple VPLS MEN, an L2PE node may support more than one VPLS, where each such VPLS has its own respective homing, that is, for each VPLS, that L2PE has a connection to one (and only one) PE node in the MEN.
Given the various nodes, attributes, and connectivity described above and known in the art, complexities arise in traffic engineering with such parameters, that is, in establishing network communications, appropriate numbers of VPLSs, connectivity, and efficient use of bandwidth. These complexities arise both in establishing these parameters in a new network for the first time as well as modifying that network if one or more factors change over time, such as when a new VPLS is added. These complexities are further complicated by the desire to include 1+1 protection in a network, whereby a first set of parameters are provided, sometimes referred to as a primary network, but are supplemented by a second set of parameters, sometimes referred to as a secondary or backup network, to operate should the first network become inoperable.
In view of the above, the preferred embodiments provide a device (e.g., network node) with sufficient processing functionality and programmed to provide traffic engineering of a VPLS network with multi-homing, with unicast and multicast traffic, and with 1+1 protection, as further detailed below.